Modern powerful hydrogenerators have a housing diameter about 20 meters and a stator core length up to 2.5 meters. An overall height of such hydrogenerators is as great as 13 meters and their weight often exceeds 1,500 tons. Obviously, when designing such machines, it should be considered that they are transported by railway or, if possible, by other kinds of transport. Therefore, not only the whole of a hydrogenerator but also its main components are manufactured detachable, sizes and weights of separate parts being confined to limiting railway gabarits and transport carrying capacity.
A hydrogenerator known to the prior art (cf. the book "Hydrogenerator Design and Construction" by A. I. Abramov et al., "Higher School" Publishing House, Moscow, 1964, p.13) comprises a stator of an annular form and a rotor, a hydrogenerator stator including a housing, a core, and a winding laid in core slots, is divided, according to its size, into two, four, or six equal (i.e. having equal angles) sectors secured to each other along their radial abutting planes. The spacers formed of a sheet of electroinsulating material are positioned between the abutting planes in the region of the core to fill the clearances. The number of these sectors is determined by possibilities of their transportation.
When a hydrogenerator is in operation, the stator core sectors are acted upon by a tangentially directed alternating electromagnetic force, its frequency being equal to n.p/60 (Hz), where n is a rotor rotational speed in revolutions per minute. That force causes stator core sectors to vibrate, and therefore to decrease this vibration the sectors should be secured to each other rigidly and tightly.
However, a hydrogenerator being in operation, tightness of abutment of stator sectors in the core region loosens influenced by a cyclic temperature rise and that results in the increase in sector vibrations and sometimes affects joints securing the core to the stator housing of a hydrogenerator. Tightening of the joints is a labor consuming operation and it fails to ensure a long-life preservation of tightness of stator abutment. The above mentioned vibrations of the stator sectors decrease the hydrogenerator reliability.